I've got a lot of machines I don't really use all the time so I decided to set them mining. They mine from about 1-5 Mhs/s each.

I recently switched to Bitcoins.cl to try it out, as I was having issues with Slush's pool not giving me good payouts given my hashrate. Bitcoins.cl does show avg. hashrate which is helpful (although it was taken down for tuning I guess recently).

Anyway I don't know if this is an issue because I switched pools but is it just a fact of life that slow miners will get stale shares a lot of the time?

Edit: Forgot to add that I'm using Phoenix or polcbm mod for all of the machines, which SHOULD support long polling, so in theory I wouldn't get this problem as much.

This was my very first question here on the forums, and I've learned the answer.

The moment a new block is created, everyone starts looking for the next one.Pool servers will divide the work up into shares, and start dishing them out to miners like you and me.

When we get a share, we start trying to crack it. Depending on the speed of your CPU/GPU it can be done quickly or slowly.When we're done our work, we submit the answer to the pool in order to be verified. Here is where the answer for your question lays.

From the time you downloaded your share from the pool, and the time you submit your share to the pool, a couple of things could happen.

You could finish processing your share before the block is found. Your pool will report "Share accepted" (or "work accepted")

A new block could have been found by someone else before your work was done. When you try to submit your share, your pool will report "Stale/invalid" because your work belongs to an older block that was already solved.

The slower your miner, the higher the chance is that you will submit a stale share.

Hope that explained it,

If my posts have helped, consider leaving a tip! 1AE5e56ivvaGMJJmLrZoLgiZXPx93CddyA

Is there anything to protect against this, or is it just the nature of slower hashing? A lot of sites always say, if you see issues with stale shares, check your miner. As far as I know Phoenix and polcbm mod have long polling built in.

In addition, I had some extremely slow machines on Slush's pool and I at least was getting some shares. The problem seems blown out of proportion on bitcoins.lc, is this because it's a lower hash rate pool?

To be honest, mining with 1-5Mh/s might not be worth the electricity to run the machines. You're most likely going to get stale shares since people can run cheap(ish) graphics cards with 25x the hashing power of your processors.

To be honest, mining with 1-5Mh/s might not be worth the electricity to run the machines. You're most likely going to get stale shares since people can run cheap(ish) graphics cards with 25x the hashing power of your processors.